Commitments and Contingent Liabilities - Commitments to Extend Credit, Participations Sold (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Commitments to extend credit
Commitments
Participations sold to other institutions	$ 66.4	$ 94.5
Standby letters of credit
Commitments
Participations sold to other institutions	$ 17.5	$ 19.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_OtherCommitmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration